Variants of SARS-CoV-2 in UK – What do we know?
December 23, 2020
In December, a new variant of SARS-CoV-2 from the UK was found to have increasing prevalence, and reports indicated that it might be more transmissible than other strains. The proportion of cases of the new variant, B.1.1.7, has been increasing since mid-October, and is currently the dominant variant in London, UK. A few of the mutations distinguishing this variant are known to cause an increase in the contagiousness of the virus in laboratory experiments. Our preliminary analysis indicates that the new variant could be 75% more transmissible than other strains1. The consequences of these mutations on the severity, vaccine efficacy and re-infection ability of SARS-CoV-2 remain unknown.
Variants of SARS-CoV-2 have been reported previously all around the world, with different mutations. Earlier this month, South Africa was announcing a new dominant variant in the country, 501.V2. Preliminary analysis also associated this variant with faster spread and a higher viral load. Mutations of the virus at the population level are expected, especially with a high number of infections being reported, and viral replication could potentially lead to genetic variations within each host. Although those changes have usually little significance, scientists monitor them to assess potential changes in transmissibility, severity and response to treatment or vaccine.
As some of the mutations of the B.1.1.7 variant have been experimentally associated with faster spread, many regions have issued a temporary ban of flights from the UK, such as several countries in Europe, or more recently, Hong Kong. While we are uncertain if the variant has become dominant by being more competitive or by chance, it is a reasonable precaution to prevent it from entering the territory, until we better understand the situation. However one caveat is that the UK is doing more genetic testing of virus strains than other countries, so it is possible that this strain could already have spread to other parts of the world.
1Leung K, Shum MH, Leung GM, Lam TT, Wu JT. Early empirical assessment of the N501Y mutant strains of SARS-CoV-2 in the United Kingdom, October to November 2020. medRxiv. 2020 Jan 1.
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